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CNET 157: 3-3 Network Technologies
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1[blank_start]Unshielded[blank_end] [blank_start]twisted[blank_end] pair (UTP) is the most common media type in LANs. It consists of four pairs of copper wire, with each pair tightly twisted together and contained in a plastic sheath or jacket.
- AUnshielded
- Btwisted
2[blank_start]UTP[blank_end] comes in numbered categories, and is up to Category 8 as of this writing. The higher the category number is, the higher the cable’s [blank_start]bandwidth[blank_end] potential. Category 5 Enhanced (Cat 5E) and Category 6 (Cat 6) are the most common in wired LANs, allowing speeds up to 10 Gbps.
- AUTP
- Bbandwidth
3UTP cabling is used in physical [blank_start]star[blank_end] networks; the maximum cable length from NIC to switch is [blank_start]100[blank_end] meters (328 feet) in LAN applications.
- Astar
- B100
4UTP cabling is susceptible to electrical [blank_start]interference[blank_end], which can cause data corruption, so it shouldn’t be used in electrically noisy environments.
- Ainterference
5[blank_start]Fiber[blank_end]-[blank_start]optic[blank_end] cabling uses extremely thin strands of glass to carry pulses of light long distances and at high data rates. Because of its capability to carry data over long distances (several hundred to several thousand meters), it’s also used in [blank_start]WAN[blank_end] applications frequently.
- AFiber
- Boptic
- CWAN
6Fiber-[blank_start]optic[blank_end] cabling isn’t susceptible to electrical interference, so, unlike UTP, it can be used in electrically noisy environments. In most cases, two strands of fiber are needed to make a network connection: one for transmitting and one for [blank_start]receiving[blank_end].
- Aoptic
- Breceiving
7Best known for its use in cable TV, [blank_start]coaxial[blank_end] cable is obsolete as a LAN medium, but it is used as the network medium for Internet access via cable modem.
- Acoaxial
8[blank_start]Coaxial[blank_end] cable was the original medium used by Ethernet in physical bus topologies, but its limitation of 10 Mbps half-duplex communication made it obsolete for LAN applications after star topologies and 100 Mbps Ethernet became the dominant standard.
- ACoaxial
9Coaxial cable in LANs can be about [blank_start]200[blank_end] meters long.
- A200
10Network technologies can use media to transmit signals in two main ways: [blank_start]baseband[blank_end] and [blank_start]broadband[blank_end]
- Abaseband
- Bbroadband
11The baseband transmission method sends digital signals in which each bit of data is represented by a pulse of [blank_start]electricity[blank_end] (on copper media) or [blank_start]light[blank_end] (on fiber-optic media). These signals are sent at a single [blank_start]fixed[blank_end] frequency, using the medium’s entire bandwidth.
- Aelectricity
- Blight
- Cfixed
12LAN technologies, such as Ethernet and token ring, use [blank_start]baseband[blank_end] transmission.
- Abaseband
13Instead of digital pulses, broadband systems use [blank_start]analog[blank_end] techniques to encode [blank_start]binary[blank_end] 1s and 0s across a continuous range of values.
- Aanalog
- Bbinary
14[blank_start]Broadband[blank_end] signals move across the medium in the form of continuous electromagnetic or [blank_start]optical[blank_end] waves rather than discrete pulses.
- ABroadband
- Boptical
15On broadband systems, [blank_start]signals[blank_end] flow at a particular frequency, and each frequency represents a channel of data. That’s why broadband systems, such as cable TV and Internet, can carry dozens or hundreds of TV channels plus Internet access on a single cable wire: Each channel operates at a different frequency. In addition, incoming and [blank_start]outgoing[blank_end] Internet data use separate channels operating at different frequencies from TV channels.
- Asignals
- Boutgoing
16[blank_start]Ethernet[blank_end], the most popular LAN technology, has many advantages, including ease of installation, scalability, media support, and low cost. It supports a broad range of transmission speeds, from [blank_start]10[blank_end] Mbps to 10 Gbps. It can operate in a bus or [blank_start]star[blank_end] physical topology and a bus or switched logical topology.
- AEthernet
- B10
- Cstar
17Every [blank_start]Ethernet[blank_end] station must have a physical or MAC address. When a frame is sent to the network medium, it must contain both [blank_start]source[blank_end] and destination MAC addresses.
- AEthernet
- Bsource
18It’s the NIC’s responsibility to transmit and receive [blank_start]frames[blank_end] and a switch’s responsibility to forward frames out the correct switch port to get the frame to its destination.
- Aframes
19Ethernet networks can accommodate frames between [blank_start]64[blank_end] bytes and [blank_start]1518[blank_end] bytes. Shorter or longer frames are usually considered errors.
- A64
- B1518
20Each frame is composed of the following:
A 14-byte frame [blank_start]header[blank_end] composed of these three fields: A 6-byte Destination MAC Address field,
a 6-byte Source MAC Address field, and a 2-byte [blank_start]Type[blank_end] field.
A [blank_start]Data[blank_end] field from 46 to 1500 bytes
A frame [blank_start]trailer[blank_end] (frame check sequence [FCS]) of 4 bytes
- Aheader
- BType
- CData
- Dtrailer
21The [blank_start]Type[blank_end] field in the frame header indicates the network [blank_start]protocol[blank_end] in the data portion. For example, this field might indicate that the Data field contains an IP, IPv6, or ARP packet, to name just a few possibilities.
- AType
- Bprotocol
22The data portion, often referred to as the “frame [blank_start]payload[blank_end],” contains network protocol header information as well as the actual data an application is transferring. The FCS in the frame trailer is an error-checking code
- Apayload
23The set of rules for each networking technology is referred to as its [blank_start]media[blank_end] access method (or “media access control”).
- Amedia
24The media access method that [blank_start]Ethernet[blank_end] uses in half-duplex mode is Carrier Sense Multiple Access with Collision Detection (CSMA/CD).
- AEthernet
25The rules for half-duplex [blank_start]Ethernet[blank_end] state that a device can send or receive data but can’t do both simultaneously.
- AEthernet
26“Multiple access” simply means that multiple computers can be listening and waiting to transmit at the same time, which brings you to “collision detection.” A [blank_start]collision[blank_end] occurs if two or more devices on the same medium transmit simultaneously.
- Acollision
27Ethernet’s collision detection method is much like a person’s; Ethernet detects, or “hears,” the other station transmit, so it knows a collision has occurred. The NIC then waits for a [blank_start]random[blank_end] period before attempting to transmit again.
- Arandom
28Remember that collisions can occur only in an Ethernet shared-media environment, which means a logical [blank_start]bus[blank_end] topology is in use.
- Abus
29The extent to which signals in an Ethernet bus topology network are propagated is called a collision [blank_start]domain[blank_end].
- Adomain
30It’s considered a [blank_start]best[blank_end]-effort delivery system, meaning that when a frame is sent, there’s no acknowledgment or verification that the frame arrived at its intended destination.
- Abest
31The error-checking code in an Ethernet frame’s trailer is called a [blank_start]Cyclic[blank_end] [blank_start]Redundancy[blank_end] Check (CRC), and is the result of a mathematical algorithm computed on the frame data.
- ACyclic
- BRedundancy
32If a frame is detected as damaged, [blank_start]Ethernet[blank_end] simply discards the frame but doesn’t inform the sending station that an error occurred (because it’s a best-effort delivery system).
- AEthernet
33The network [blank_start]protocol[blank_end] or, in some cases, the [blank_start]application[blank_end] sending the data is responsible for resending damaged or missing data, not Ethernet.
- Aprotocol
- Bapplication
34[blank_start]Half[blank_end]-duplex communication means a station can transmit and receive data but not at the same time, much like a two-way radio.
- AHalf
35When Ethernet is implemented as a logical bus topology (using [blank_start]hubs[blank_end]), NICs can operate only in half-duplex mode and must use the CSMA/CD access method.
- Ahubs
36[blank_start]Full[blank_end]-duplex mode, by definition, means a NIC can transmit and receive simultaneously.
- AFull
37Ethernet NIC is operating in full-duplex mode connected to a switch, CSMA/CD isn’t used because a [blank_start]collision[blank_end] can’t occur in full-duplex mode.
- Acollision
38Ethernet standards are generally expressed in one of two ways. One way is using the [blank_start]IEEE[blank_end] document number defining the standard.
- AIEEE
39The second way of expressing an Ethernet standard is to use the [blank_start]XBaseY[blank_end] terminology.
- AXBaseY
40Most IEEE 802.3 documents describe the transmission speed, type of transmission, and length or type of cabling and are designated with terms such as 100BaseT. In 100BaseT, for example, the “100” designates the [blank_start]speed[blank_end] of transmission (100 Mbps), the “Base” indicates a [blank_start]baseband[blank_end] signaling method, and the “T” specifies [blank_start]twisted[blank_end]-pair cabling.
- Aspeed
- Bbaseband
- Ctwisted
41All the BaseT Ethernet standards use a physical star topology.
- ATrue
- BFalse
42[blank_start]10BaseT[blank_end] Ethernet, defined by IEEE 802.3i, has been the mainstay of Ethernet networks since the early 1990s. It runs over Category 3 or higher UTP cabling and uses two of the four wire pairs.
- A10BaseT
43 The rule for expanding a 10BaseT network with hubs is that no more than [blank_start]four[blank_end] hubs can be placed between two communicating workstations.
- Afour
44[blank_start]100BaseTX[blank_end] (often called simply “100BaseT”), defined by IEEE 802.3u, is still the most common Ethernet variety. It runs over Category 5e or higher UTP cable and uses two of the four wire pairs: one to transmit data and the other to receive data.
- A100BaseTX
45In environments that aren’t conducive to using copper wiring to carry network data (such as electrically noisy settings) or where the cable run length exceeds the reach of twisted-pair wiring, the only real choice in a wired network is fiber optics. In these settings, [blank_start]100BaseFX[blank_end] (with the F indicating “fiber optic”), which uses two strands of fiber-optic cable, is often the best choice of network technology
- A100BaseFX
46[blank_start]1000BaseT[blank_end] Ethernet, released as the IEEE 802.3ab standard, supports 1000 Mbps Ethernet (usually called “Gigabit Ethernet”) over Category 5e or higher UTP cable.
- A1000BaseT
47Unlike 10BaseT and 100BaseT Ethernet, [blank_start]1000BaseT[blank_end] Ethernet doesn’t dedicate a wire pair to transmitting or receiving. Each wire pair is capable of transmitting and receiving data simultaneously, thereby making the 1000 Mbps data rate possible in both half-duplex and full-duplex modes.
- A1000BaseT
48The IEEE ratified the 802.3bz specification that defines 2.5 and 5 Gigabit Ethernet running over Cat 5e/6 cabling. Because the new [blank_start]2.5[blank_end]/[blank_start]5[blank_end] GBaseT Ethernet standard works over Cat5e and Cat6 cabling, there is no need for a change in the wiring infrastructure, as most cabling plants use Cat5e or Cat6.
- A2.5
- B5
49The 2006 IEEE 802.3an standard defines 10 Gigabit Ethernet as running over [blank_start]four[blank_end] pairs of Category 6A or Category 7 UTP cabling. Unlike the other BaseT Ethernet standards, 10GBaseT operates only in full-duplex mode, so there is no such thing as a 10 Gbps hub—only [blank_start]switches[blank_end].
- Afour
- Bswitches
50[blank_start]100BaseT4[blank_end] Ethernet uses all four pairs of wires bundled in a UTP cable. The one advantage that 100BaseT4 has over 100BaseTX is the capability to run over Category 3 cable.
- A100BaseT4
51Although these differences from 100BaseTX might seem like good ideas, 100BaseT4 never caught on and is essentially obsolete.
- ATrue
- BFalse
52[blank_start]1000BaseLX[blank_end] uses fiber-optic media; the “L” stands for “long wavelength,” the kind of laser used to send signals across the medium. These lasers operate at wavelengths between 1270 and 1355 nanometers and work with single-mode fiber (SMF) and multimode fiber (MMF).
- A1000BaseLX
53Although the 1000BaseLX standard specifies a maximum cable segment length of [blank_start]5000[blank_end] meters, some manufacturers have extended it by using specialized and proprietary optical transceivers. Cisco Systems, for example, offers 1000BaseLH (“LH” stands for “long haul”), which provides a maximum cable segment length of [blank_start]10,000[blank_end] meters over SMF cable. For extremely long-distance Gigabit Ethernet communication, 1000BaseZX, another Cisco product, is capable of distances up to [blank_start]100,000[blank_end] meters over SMF cable.
- A5000
- B10,000
- C100,000
54[blank_start]1000BaseSX[blank_end] uses fiber-optic media; the “S” stands for “short wavelength.” These lasers operate at wavelengths between 770 and 860 nanometers and work only with MMF cable.
- A1000BaseSX
55[blank_start]1000BaseCX[blank_end] uses specially shielded, balanced, copper jumper cables; the “C” stands for “copper,” the kind of electrical signaling used. These jumper cables might also be called “twinax” (short for “twin-axial”) or “short-haul” copper cables. Segment lengths for 1000BaseCX cables top out at [blank_start]25[blank_end] meters
- A1000BaseCX
- B25
56The 802.3ae standard. It is defined to run only on [blank_start]fiber[blank_end]-optic cabling, but the 10 Gigabit Ethernet standard specifies a maximum distance of 40 km, compared with just 5 km for 1000BaseLX Gigabit Ethernet.
- Afiber
57[blank_start]10GBaseSR[blank_end]—Runs over short lengths (between 26 and 82 meters) on MMF cabling. Applications are likely to include connections to high-speed servers, interconnecting switches, and SANs.
[blank_start]10GBaseLR[blank_end]—Runs up to 10 km on SMF cabling and is used for campus backbones and MANs.
[blank_start]10GBaseER[blank_end]—Runs up to 40 km on SMF cabling; used primarily for MANs.
[blank_start]10GBaseSW[blank_end]—Uses MMF cabling for distances up to 300 meters; used for SONET campus network applications.
[blank_start]10GBaseLW[blank_end]—Uses SMF cabling for distances up to 10 km; used for SONET WAN applications.
[blank_start]10GBaseEW[blank_end]—Uses SMF cabling for distances up to 40 km; used for SONET WAN applications.- A10GBaseSR
- B10GBaseLR
- C10GBaseER
- D10GBaseSW
- E10GBaseLW
- F10GBaseEW
58IEEE [blank_start]802.3ba[blank_end] was ratified in 2010. Fiber-optic cabling is the primary medium for supporting these speeds, although there are provisions to use special copper assemblies over short distances. Related standards that support 100 Gbps include 802.3bj and 802.3bm.
- A802.3ba
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- Computer Science Quiz on CNET 157: 3-3 Network Technologies, created by Jillian Jenkins on 04/02/2020.
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- Jillian Jenkins
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